In digital communications networks, particularly in SDH networks (SDH=Synchronous Digital Hierarchy), a database containing data about the current network configuration is provided for each network element. Network elements are also referred to as "nodes".
U.S. Pat. No. 5,524,205 discloses a method of making protected changes to data stored in memory blocks in a database. The database described there is implemented on a hard disk and contains data about the state of a node in a data processing system, which are updated in the form of so-called transactions. A "transaction" corresponds to a group of changes made to change at least one node of the system from one state to the next. The database and two buffers ("undo buffer" and "redo buffer") form a database system which is to ensure that the system can be restarted from a defined state if disturbances should occur during a transaction. To accomplish this, the database system performs a recovery in which prior to the beginning of the transaction, data about the latest state of the node are written into one of the buffers ("undo buffer"), and in which during the transaction, data about the next state of the node are written into the other buffer ("redo buffer"). If the transaction was not disturbed, the data stored in the redo buffer describe the current state of the node. If the transaction was disturbed, the data stored in the undo buffer describe the current state from which the system can be restarted. In the method and system described in U.S. Pat. No. 5,524,205, read/write accesses to two buffers are necessary, which signifies complex and slow memory management.
An article by S. Colombo et al, "Technologie der SDH-Netzelemente: die Software-Plattform", Elektrisches Nachrichtenwesen, a journal published by the applicant, 4th Quarter 1993, pages 321-327, describes the use of object-oriented databases in network elements of an SDH communications network and addresses the subjects of memory management and persistency. A method or apparatus for making protected changes to the stored data is not described. A general description of SDH network elements and their management can be found in the same journal, on pages 329-337, in an article by M. P. Bosse et al, "Management von SDH-Netzelementen: eine Anwendung der Informationsmodellierung".